Field of the Invention
This disclosure relates to an image forming apparatus on the basis of an electrophotographic system such as copying machines and printers.
Description of the Related Art
In the related art, as an image forming apparatus on the basis of an electrophotographic system, an image forming apparatus provided with an intermediate transfer belt as an intermediate transfer member is known. In the image forming apparatus of the related art, voltage is applied from a first voltage supply (power circuit) to a primary transfer member arranged on a portion opposing a photosensitive drum via an intermediate transfer belt, so that a primary transfer potential is generated at a primary transfer portion of the intermediate transfer belt that comes into contact with the photosensitive drum. Then, with a potential difference generated between the photosensitive drum and the intermediate transfer belt, a toner image formed on a surface of the photosensitive drum as an image bearing member is primarily transferred onto the intermediate transfer belt (primary transfer process). Subsequently, this primary transfer process is repeatedly performed for toner images in the respective colors to form a toner in a plurality of colors on the surface of the intermediate transfer belt. Subsequently, as a secondary transfer process, the toner images in a plurality of colors formed on the surface of the intermediate transfer belt are secondarily transferred as a job lot to a surface of a recording material such as paper by applying voltage from a second voltage supply to a secondary transfer member. The toner images transferred as a job lot are then fixed to the recording material by a fixing device.
Japanese Patent Laid-Open No. 2011-232785 discloses a configuration of a rigid member such as a metallic roller is brought into contact with the intermediate transfer belt as the primary transfer portion to which voltage is applied from the first voltage supply. In order to prevent the photosensitive drum from being worn by the metallic roller, the metallic roller proposes, a configuration in which the metallic roller is arranged on the downstream side of a contact area between the intermediate transfer belt and the photosensitive drum in a direction of movement of the intermediate transfer belt is proposed.
However, in a primary transfer configuration in Japanese Patent Laid-Open No. 2011-232785, since a contact member is a rigid member, the intermediate transfer belt may be bent in a width direction orthogonal to the direction of movement of the intermediate transfer belt. Specifically, bending of the intermediate transfer belt may occur in a boundary portion between the intermediate transfer belt and the contact area of the contact member in the width direction. If the bending occurs in the boundary portion in the width direction, unevenness in contact may occur in the contact area between the intermediate transfer belt and the photosensitive drum, so that there arises a problem of an occurrence of transfer failure.